Corrosion resistance of in-situ Mg–Al hydrotalcite conversion film on AZ31 magnesium alloy by one-step formation

doi:10.1016/S1003-6326(15)63799-2

Transactions of Nonferrous Metals Society of China

Volume 25, Issue 6, June 2015, Pages 1917-1925

https://doi.org/10.1016/S1003-6326(15)63799-2 Get rights and content

Abstract

In situ growth of nano-sized layered double hydroxides (LDH) conversion film on AZ31 alloy was synthesized by a urea hydrolysis method. The formation mechanism of the film was proposed. Firstly, the dissolved Mg²⁺ ions deposited into a precursor film consisted of MgCO₃ and Mg₅(CO₃)₄(OH)₂· 4H₂O; secondly, the precursor translated into the crystalline Mg(OH)₂ in alkaline conditions; finally, the Mg²⁺ ions in Mg(OH)₂ were replaced by Al³⁺ ions, Mg(OH)₂ translated into the more stable LDH structure, simultaneously, the OH⁻ ions in the interlayer were exchanged by, thus led to the formation of the LDH (Mg₆Al₂(OH)₁₆CO₃·4H₂O) film. The results indicated that the LDH film characterized by interlocking plate-like nanostructures and ion-exchange ability significantly improved the corrosion resistance of the AZ31 Mg alloy.

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Different Mg(Li)-M (M: Al, Fe, Cr) layered double hydroxides (LDHs) films were successfully prepared on Mg-Li alloy with in-situ growth method. Further, the corrosion inhibitor was screened and the tartaric acid-loaded LDHs (Mg(Li)-M LDHs-TA) films were prepared. The morphologies, compositions, structures and corrosion resistance of the LDHs films changed before and after tartaric acid loading. The Mg(Li)-Cr LDHs-TA film exhibits the most excellent corrosion resistance with a current density i_corr 1.5 × 10^–9 A cm^–2. Moreover, corrosion mechanisms of the Mg(Li)-M LDHs and Mg(Li)-M LDHs-TA films were discussed in combination with Scanning Vibrating Electrode Technique.
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: Foundation item: Project (51241001) supported by the National Natural Science Foundation of China; Project (ZR2011EMM004) supported by Shandong Provincial Natural Science Foundation, China; Project (TS20110828) supported by Taishan Scholarship Project of Shandong Province, China; Project (2014TDJH104) supported by SDUST Research Fund, Joint Innovative Center for Safe and Effective Mining Technology and Equipment of Coal Resources of Shandong Province, China

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Corrosion resistance of in-situ Mg–Al hydrotalcite conversion film on AZ31 magnesium alloy by one-step formation

Abstract

Materials Letters

Transactions of Nonferrous Metals Society of China

Transactions of Nonferrous Metals Society of China

Transactions of Nonferrous Metals Society of China

Materials Letters

Colloids and Surfaces B: Biointerfaces

Journal of alloys and compounds

Surface and Coatings Technology

Materials Chemistry and Physics

Corrosion Science

Corrosion Science

Corrosion Science

Corrosion Science

Scripta Materialia

Corrosion science

Corrosion Science

Thin Solid Films

Surface and Coatings Technology

Chemical Engineering Science

Transactions of Nonferrous Metals Society of China

Applied Clay Science